1. Field of the Invention
The present invention relates to a semiconductor integrated circuit, and more specifically to a semiconductor integrated circuit including therein an electrically writable non-volatile semiconductor memory and an error detection and correction circuit for detecting and correcting an error of data read out from the semiconductor memory.
2. Description of Related Art
In this type of conventional semiconductor integrated circuit, data is read out from a data bit memory section of an electrically writable non-volatile semiconductor memory, and supplied to a data selection circuit and an error detection and correction circuit. Simultaneously, a check bit or bits are read out from a check bit memory section of the electrically writable non-volatile semiconductor memory, and also supplied to the error detection and correction circuit. On the basis of the data read out from the data bit memory section and the check bit or bits read out from the check bit memory section, the error detection and correction circuit generates a detection signal indicative of whether or not an error exists in the read-out data. In addition, the error detection and correction circuit outputs the read-out data without modification to the data selection circuit if no error exists in the read-out data, and also generates corrected data to the data selection circuit if the error exists in the read-out data.
Furthermore, on the basis of a selection signal read out from an output selection bit memory section of the electrically writable non-volatile semiconductor memory, the data selection circuit selects and outputs one of the data read out from the data bit memory section and the corrected data outputted from the error detection and correction circuit.
When the above mentioned conventional semiconductor integrated circuit is assembled in a package or a system both of which do not allow to erase the content of the memory, the content of the output selection bit memory section of the electrically writable non-volatile semiconductor memory can no longer be modified. In other words, it is impossible to voluntarily or freely set the selection signal. As a result, after the assembling, an operation verifying test of the error detection and correction circuit cannot be performed.